In non-proportionally representative assemblies, where the tendency to gravitate into two major parties or party groupings operates strongly, Government and Opposition roles can go to the two main groupings serially in alternation. In this context, the opposition forms a recognised, even semi-official "government-in-waiting". Its "opposing" can degenerate into a charade pending the eventual exchange of roles and (re-)occupation of the Treasury benches.
The more proportional a representative system, the greater the likelihood of muliple political parties appearing in the parliamentary debating chamber. Such systems can foster multiple "opposition" parties which may have little in common and minimal desire to form a united bloc opposed to the government of the day.
Some well-organised democracies, dominated long-term by a single faction, reduce their parliamentary opposition to tokenism. Singapore exemplifies a case of a numerically weak opposition; South Africa under the apartheid regime maintained a long-term imbalance in the parliament.
By their very presence in the debating chamber, parliamentary oppositions recognise the legitimacy of the system of politics, and thus may share many of the views of the government. The Opposition in such cases can justly claim the title of His/Her Majesty's Loyal Opposition. Often one must go the extra-parliamentary oppositions to find radical or fundamental alternatives to the status quo.